This invention relates to a method and a mechanism for converting vibration induced rotation into translational motion.
Conventional threaded bodies e.g. nut and bolt, stud and block are engaged by means of some sort of device like a screwdriver, wrench or gripping device which is used to rotate one of the threaded bodies relative to the other with sliding contact between the mating threads to translate the two bodies into or out of engagement with each other. Each pair of bodies requires individual driver action, at least one of the pair must be designed to accept the driver and the driven body must, also, be accessible to the driver. The threading or screwing operation can become difficult when the driven body is very small. At any size there is the danger that the driving force balanced against the frictional force of the sliding threads can exceed the shear strength of the body and break it. The driven body must have a defined length: it typically requires an end configured to receive a driver.
Common vibration techniques have been used to loosen and tighten nuts and bolts using rotary vibration pulses, Russian Patent Nos. SU 977144-A, SU 954203-A and to loosen frozen nuts German Patent No. DE2815391-AT. Vibration has also been used to move powder in a helical chamber, Russian Patent No. SU 5229063-A, and in a circular path, German Patent No. DE3303745-A1. In one case vibration induced rotation has been used to drive individual screwdrivers in sleeves, each screwdriver being engaged with a separate screw. The rotation of each screwdriver drives its associated screw in the conventional way.
It is therefore an object of this invention to provide a method and mechanism for converting vibration induced rotation into translational motion.
It is a further object of this invention to provide such a method and mechanism which drives threaded bodies to engage and/or to disengage without a driver, independent of their size or length and without imposing damaging shear forces or causing cross-threading.
It is a further object of this invention to provide such a method and mechanism which operates over a wide range of frequencies and is relatively independent of the amplitude of the actuating vibration.
It is a further object of this invention to provide such a method and mechanism which can function as a speed reducer to decrease the speed of the actuating vibration relative to that of the rotation of the translating body by a factor which is a function of the gap between the threads.
It is a further object of this invention to provide such a method and mechanism in which the speed of the vibration and of the translating body can be used to calculate the actual gap between the threads.
It is a further object of this invention to provide such a method and mechanism which has a unique and surprising motion that engrosses and intrigues observers making for an amusing device or toy.
The invention results from the realization that a truly new and unique method and mechanism for converting vibration induced rotation into translational motion useful for driverless actuation of screws, speed reduction and screw gap tolerance monitoring, for example, can be effected by engaging the threads of two threaded bodies and vibrating one of those bodies to induce rolling contact rotation between them to generate a net translational motion of the other body along the axis of the threads of the translating body.
This invention features a mechanism for converting vibration induced rotation to translational motion. There are first and second threaded bodies, one having external threads the other having internal threads for engaging the external threads. There is a gap between the threads and an actuator coupled to one of the bodies for vibrating that body to induce rolling contact rotation between the threads of the body relative to each other and generating a net translational motion of the other body along the axis of the threads of the translating body.
In a preferred embodiment the threads may be helical, the bodies may include a screw and a nut, the actuator may be a mechanical vibrator. The actuator may induce vibration in each of two perpendicular axes which are mutually perpendicular with the axis of the threads of the translating body, the vibrations may be sinusoidal, and the rotational motion may be circular. The actuator may include a piezoelectric device. The center of mass of the translating body may describe a helical path having a smaller pitch than the pitch of the threads on the bodies. The speed of rotation of the translating body may be reduced relative to the speed of the vibration in proportion to the ratio of the gap to the diameter of the translating body.
The invention also features a method of converting vibration induced rotation into translational motion including engaging the threads of first and second threaded bodies, one having internal threads the other external threads with a gap between them. One of the bodies is vibrated to induce rolling contact rotation between the threads of the bodies relative to each other and generating a net translational motion of the other body along the axis of the threads of the translating body.
In one embodiment, the actuator includes a motor attached to the first or second body, the motor having a shaft, the actuator further including an unbalanced mass on the shaft which causes vibrations. In one example the first body includes a block with at least one internally threaded hole therein and the second body is an externally threaded shaft. In another example, the first body includes a threaded shaft and the second body is a nut.
One method of converting vibration induced rotation into translational motion in accordance with this invention includes engaging the threads of first and second threaded bodies, one having internal threads the other external threads with a gap between them; and vibrating the first body to induce rolling contact rotation between the threads of the bodies relative to each other and generating a net translational motion of the second body along the axis of the threads of the second body. Preferably, the threads are helical. Vibrating typically includes attaching an actuator to the first body. The actuator induces a vibration in each of two perpendicular axes which are mutually perpendicular with the axis of the threads of the second body. In the preferred embodiment, the vibrations are sinusoidal, the rotational motion is circular, and the center of mass of the second body describes a helical path having a smaller pitch than the pitch of the threads on the bodies. Also, the speed of rotation of the second body is reduced relative to the speed of the vibrations in proportion to the ratio of the gap to the diameter of the second body.
One mechanism for converting vibration induced rotation into translational motion in accordance with this invention includes a first threaded body and a second threaded body wherein one said body has external threads and the other said body has internal threads. There is a gap between the internal and external threads and means, coupled to the first body, for vibrating that body to induce rolling contact rotation between the threads of the bodies relative to each other and generating a net translational motion of the second body along the axis of the threads of the second body. In one embodiment, the means is an actuator, configured to induce a vibration in each of two perpendicular axes which are mutually perpendicular with the axis of the threads of the second body.
A preferred mechanism for converting vibration induced rotation into translational motion in accordance with this invention includes a first threaded body and a second threaded body wherein one body has external threads and the other body has internal threads. There is a gap between the threads and an actuator coupled to the first body and configured to induce a sinusoidal vibration in each of two perpendicular axes, the axes being mutually perpendicular with an axis of the threads of the second body.